There has been recent interest in systems that enable access to computer sourced data and applications via devices (often referred to as “client” devices) that are simpler and less costly than the traditional personal computer (PC). Two examples of these so-called “client” devices are web-pads and remote-desktop devices.
Web-pads (e.g., the reference design from National Semiconductor, Inc., see http://www.national.com/appinfo/solutions) carry just enough processing power to run a browser application, which is perhaps a lightweight or thin version of the usual PC browser program. Data and applications are transmitted to the device in the form of web pages that are typically sourced from servers on the Internet. By employing a Hypertext Mark-Up Language (HTML) format, a number of different screen sizes, and hence client form-factors, can be supported.
Unfortunately, this prior art approach incurs the cost of requiring sufficient processing power at the client to run the browser application. This processing requirement is significantly increased when support is required for popular multimedia data-types and their associated plug-ins, such as, Flash™ files (Flash™ player available from Macromedia, Inc. of San Francisco, Calif.), audio files (e.g., MP3 audio files), and video files.
In the case of a remote-desktop device, a local PC acts as the server, and transmits the data necessary to support a remote instance of its desktop interface (e.g., Windows™) on the client's screen. In this prior art approach, the graphics system calls (e.g., draw rectangle and draw text string) are transmitted between an application and the rendering software/hardware. For example, “Windows Terminal Services”, which is available from Microsoft, Inc. of Redmond, Wash., and “WinFrame”, which is available from Citrix Systems, Inc. of Fort Lauderdale, Fla., transmit the graphics system calls (e.g., draw rectangle and draw text string) between an application and the rendering software/hardware.
One disadvantage of this approach is that the remote-desktop device requires sufficient processing power to render the graphics system calls that the device receives. For certain applications, these processing power requirements exceed the maximum size restrictions, maximum weight restrictions, and maximum power consumption requirements of the applications.
Furthermore, although this prior art approach provides tolerable results when simple shapes and text are involved, unfortunately, when multimedia data-types are involved, this prior art approach performs poorly, if at all. For example, in the case of video data, the application renders directly to the screen. Consequently, if video is supported at all, every frame must be sent as a bitmap to the client, which can lead to high bandwidth requirements, especially where wireless links are concerned.
Both prior art approaches also assume that a small client screen size precludes conventional, PC-like, interaction, and that such PC-like interaction is not possible for very small displays (e.g., displays of a cell-phone or a display of a wrist-watch)
Another disadvantage of these approaches is that the quality of the communication link between the PC the portable display unit is not adequately addressed. As can be appreciated, the quality of the communication link is very important. A present challenge is that a number of ever-changing factors (e.g., noise and interference in the environment) can adversely affect the transmission of the information between the PC and the display unit. When the quality of the communication link is not adequately addressed in the transmission scheme, considerable risk is taken that data may be lost or otherwise corrupted.
Accordingly, it would be desirable for there to be a mechanism that enables low cost, compact, lightweight, low power client devices to display media-rich information and that overcomes the disadvantages set forth previously.